CN110643834B

CN110643834B - Extraction system for separating calcium from calcium-containing brine by using secondary amide/alkyl ester composite solvent to extract lithium, extraction method and application thereof

Info

Publication number: CN110643834B
Application number: CN201911089222.4A
Authority: CN
Inventors: 杨立新; 田翔; 刘长; 李海博; 李聪; 周钦耀
Original assignee: Xiangtan University
Current assignee: Xiangtan University
Priority date: 2019-11-08
Filing date: 2019-11-08
Publication date: 2021-05-25
Anticipated expiration: 2039-11-08
Also published as: CN110643834A

Abstract

The invention discloses an extraction system, an extraction method and application of lithium extracted by separating calcium from calcium-containing brine by using a secondary amide/alkyl ester composite solvent. The extraction system contains secondary amide and alkyl ester which are respectively composed of single compounds or a mixture of more than two compounds, the total number of carbon atoms in molecules is respectively 12-18 and 8-20, and the freezing point of the extraction system is less than 0 ℃. The volume ratio of the organic phase to the brine phase is 1-10: 1, and the brine density is 1.30-1.56 g/cm³And carrying out single-stage or multi-stage countercurrent extraction on the brine at the pH value of 1-7 and the temperature of 0-50 ℃, carrying out back extraction to obtain a low calcium-lithium ratio water phase, and respectively obtaining lithium chloride, lithium carbonate and lithium hydroxide through concentration, impurity removal and preparation. The excellent effects of the present invention: the secondary amide extractant has simple molecular structure and easy production, and the alkyl ester improves the properties of the composite solvent such as viscosity and the like; li⁺The multi-stage extraction rate is high, the lithium-calcium separation coefficient is large, and the consumption of acid and alkali by water back extraction is low; the extraction and separation process flow is short, the dissolution loss of an extraction system is small, and the method is suitable for the development of oil field brine.

Description

Extraction system for separating calcium from calcium-containing brine by using secondary amide/alkyl ester composite solvent to extract lithium, extraction method and application thereof

Technical Field

The invention relates to a method for extracting lithium from calcium-containing brine, in particular to an extraction system for separating calcium from the calcium-containing brine by using a composite solvent to extract lithium, an extraction method and application thereof.

Background

The method has abundant oil field underground brine in the south wing mountain area in the west of the Qinghai firewood basin in China, the resource storage capacity of the method can be comparable to that of the salt lake in the Qinghai firewood basin, and the method is a rare multi-element coexistence extra-large mineral deposit in the world and has great industrial development value. The potassium, boron, lithium, iodine and other useful components are abundant and high in content, the resource occurrence state is greatly different from the developed salt lake resource types, the calcium chloride type brine in the Sulin classification has the characteristics of high salinity, high calcium, low magnesium and low sulfate radical, and the calcium chloride content is up to 30.8-43.0% after the calcium chloride type brine is subjected to solarization and concentration in a salt field.

In recent years, valuable element lithium is extracted from brine with high calcium-lithium ratio and is valued, the separation of calcium and lithium is a technical key, and the existing calcium-lithium separation methods mainly comprise two methods: (1) the bittern admission method is to mix mirabilite or bittern containing sulfate radical with calcium containing bittern to eliminate calcium sulfate precipitate and separate calcium from lithium. The Gaoyangyuan and the like react with a calcium source in high-calcium old brine by utilizing a sodium sulfate resource of a salt lake or nearby sodium sulfate resource to carry out old brine decalcification (CN104817096B), and the method can generate a large amount of calcium sulfate precipitation and has serious lithium ion entrainment loss. (2) a freeze crystallization method in which a calcium salt in brine is precipitated at a low temperature by utilizing the change in solubility of calcium chloride with temperature. Plum ice and the like evaporate oil field water to a specific gravity of 1.40-1.54, and freeze the oil field water at 0-30 ℃ for 3-15 days to obtain lithium-rich brine (CN103508472A), wherein the method has long time and the reduction degree of the calcium-lithium mass ratio is limited.

In other methods for separating calcium from brine, a chelating cation exchange resin column is adopted to remove more than divalent metal cations (CN108840354A) in a lithium-containing solution at a pH value of 10-12 for Qinxing and the like, a nanofiltration device is adopted for removing calcium and magnesium impurities (CN106048218A) in a high-salt lithium chloride mixed solution for Guodingjiang and the like, calcium and magnesium ions (CN105712383A) in a lithium-rich solution are removed for Caomizhen and the like by an extraction method with P204 as an extraction agent and sulfonated kerosene as a slow release agent, and the methods are only suitable for deep purification treatment of low-concentration calcium and magnesium-containing brine. At present, few documents relating to research on high-calcium-lithium-ratio oil field brine are available, and particularly, no document is reported for calcium-lithium separation of high-calcium-lithium-ratio brine by using solvent extraction method, which is attributed to Ca²⁺The valence layer has empty 3d orbit, strong coordination ability, ion hardness and Mg²⁺Is obviously different fromThe fact that separation of high calcium-lithium ratio brines is more difficult than separation of high magnesium-lithium ratio brines has led to the development of lithium resources in oil field brines that has not been realized to date.

However, the solvent extraction method achieves the purpose of separating lithium calcium or lithium magnesium by utilizing the specific extraction performance of an organic solvent on lithium ions, is considered as the most promising lithium extraction method for the salt lake brine with high magnesium-lithium ratio, and can also be applied to the oil field brine with high calcium-lithium ratio, and the advantages and disadvantages of the extractant and the discovery of a new extractant are the key points of the technical process. The alkyl ester is used as a neutral solvent with rich sources and stable property without strong acid and alkali catalysis, is beneficial to two-phase separation, and can form a new extraction system by combining with other effective components. After the high-calcium lithium ratio brine is converted into the low-calcium lithium ratio brine through the lithium-calcium separation, basic chemical products such as lithium chloride, lithium carbonate and lithium hydroxide which are particularly needed in the market can be prepared.

Disclosure of Invention

The object of the present invention is to provide an economical and efficient extraction system for separating calcium from calcium-containing brine using a secondary amide/alkyl ester composite solvent, extraction method and use thereof, in view of the disadvantages of the prior art methods.

The technical scheme and the technical process provided by the invention are as follows:

1. an extraction system for separating calcium from calcium-containing brine by using a secondary amide/alkyl ester composite solvent to extract lithium, wherein the extraction system contains substances A and B; wherein the A-type substance is a secondary amide and consists of a single compound or a mixture of more than two compounds; wherein the single compound has a structure as shown in formula (I):

wherein R is₁Selected from C2-C12 alkyl or C3-C12 cycloalkyl containing single ring structure, R₂Selected from C1-C11 alkyl or C3-C11 cycloalkyl containing single ring structure, and R₁And R₂The sum of the numbers of carbon atoms contained in the two groups being 11 to 17, wherein the alkyl group or the cycloalkyl group includes the same groupsIsomer (due to R)₁、R₂Is variable when R₁、R₂When uniquely identified, class A is a single compound, and mixtures thereof refer to compounds that follow R₁、R₂A mixture of two or more compounds produced by the change of (1);

wherein the B-type substance is alkyl ester and consists of a single compound or a mixture of more than two compounds; wherein the single compound has a structure as shown in formula (II):

wherein R is₃Selected from C1-C12 alkyl, R₄Selected from C1-C15 alkyl, and R₃And R₄The sum of the number of carbon atoms contained in the two alkyl groups is 7 to 19, wherein the alkyl group contains various linear isomers or isomers with branched chains (due to R)₃、R₄Is variable when R₃、R₄When uniquely identified, class B is a single compound, and mixtures thereof refer to compounds that follow R₃、R₄A mixture of two or more compounds produced by the change of (1);

the freezing point of the extraction system containing the substances A and B is less than 0 deg.C (the freezing point of a single component constituting the extraction system may be less than, equal to or greater than 0 deg.C, the conditions for the extraction system of the present invention can be satisfied when the freezing point of the single component is less than 0 deg.C, and when the freezing point of the single component is greater than or equal to 0 deg.C, the single component may be mixed with other components having freezing points less than 0 deg.C, and dissolved to finally form a mixture having a freezing point less than 0 deg.C).

In the extraction system, the volume percentage of the A-type substances in the whole organic phase for extraction is 50-100%, and the end value is not 100%; the volume percentage of the B-type substance in the whole organic phase is 0-50% by taking the synergistic effect, and the end value is not 0%.

The extraction system consisting of the substances A and B also comprises diluent No. 260 solvent oil, No. 300 solvent oil or sulfonated kerosene for dilution.

2. An extraction process for separating calcium from calcium-containing brine using a secondary amide/alkyl ester composite solvent to extract lithium, comprising the steps of:

s1, taking calcium-containing brine as a brine phase before extraction; wherein, in the calcium-containing brine, the concentration of lithium ions is 0.09-24 g/L, the concentration of calcium ions is 145-277 g/L, the concentration of chloride ions is 271-511 g/L, the mass ratio of calcium to lithium is 7.5-1900: 1, and the brine density is 1.30-1.56 g/cm at 20 DEG C³Adjusting the pH value of the brine to be 1-7 by using hydrochloric acid or sulfuric acid;

s2, taking the extraction system in the step 1 as an organic phase before extraction;

s3, mixing the organic phase before extraction and the brine phase before extraction according to the volume ratio of 1-10: 1, performing single-stage extraction or multi-stage countercurrent extraction, and separating the two phases to obtain a loaded organic phase and an extracted brine phase.

The calcium-containing brine also contains one or more of sodium ions, potassium ions, magnesium ions, iron ions, ferrous ions, boric acid or borate ions.

The calcium-containing brine includes, but is not limited to, lithium-containing oil field brine or lithium-containing underground brine.

Further, in the step S3, the extraction temperature is 0-50 ℃; the mixing of the two phases is carried out by stirring, and the separation of the two phases after extraction is carried out by a centrifugal separation mode or a clarification and sedimentation mode.

Further, after the step S3, the method further includes the steps of:

s4, taking water as a back extraction agent, carrying out single-stage back extraction or multi-stage counter-current back extraction on the loaded organic phase, wherein the volume ratio of the back extraction agent to the loaded organic phase is 1: 1-20, and carrying out two-phase separation to obtain a back-extracted organic phase and a back-extracted aqueous phase;

s5, returning the organic phase after back extraction to the step S2, and realizing the recycling of the extraction system.

Further, in the step S4, the back extraction temperature is 0-50 ℃; the two-phase mixing is carried out by a stirring mode, and the two-phase separation after back extraction is carried out by a centrifugal separation mode or a clarification and sedimentation mode.

3. Use of an extraction method for separating calcium from a calcium-containing brine using a secondary amide/alkyl ester composite solvent to extract lithium in obtaining a lithium product, lithium chloride, further comprising the steps of, after said step S4:

s6, further removing oil, purifying and concentrating the back-extracted water phase, and then adding an impurity removing agent to remove residual calcium ions and a small amount of magnesium ions to obtain a lithium chloride solution after water phase refining; the impurity removing agent is one or more compounds of sodium sulfate, sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

s7, concentrating, crystallizing, separating and drying the refined lithium chloride solution to obtain the lithium chloride product.

4. Use of an extraction process for extracting lithium by separating calcium from a calcium-containing brine using a secondary amide/alkyl ester composite solvent to obtain lithium carbonate as a lithium product, said extraction process further comprising, after said step S4, the steps of:

and S8, adding sodium carbonate into the refined lithium chloride solution to obtain lithium carbonate precipitate, and separating and drying the lithium carbonate precipitate to obtain a lithium carbonate product.

5. Use of an extraction method for separating calcium from a calcium-containing brine using a secondary amide/alkyl ester composite solvent to extract lithium in obtaining a lithium product, lithium hydroxide, comprising the steps of, after said step S4:

s9, electrolyzing the refined lithium chloride solution to obtain a lithium hydroxide product, and simultaneously by-producing hydrogen and chlorine, wherein the hydrogen and chlorine can be used for producing hydrochloric acid;

or after the step S6, the method further includes the steps of:

s8, adding sodium carbonate into the refined lithium chloride solution to obtain lithium carbonate precipitate, and separating and drying the lithium carbonate precipitate to obtain a lithium carbonate product;

and S10, adding calcium hydroxide emulsion into the prepared lithium carbonate, carrying out solid-liquid reaction, separating to obtain a lithium hydroxide solution, and concentrating, crystallizing and drying the lithium hydroxide solution to obtain a lithium hydroxide product.

The secondary amide type compound used in the examples of the present invention was synthesized by reacting an organic acid chloride or acid anhydride with a primary amine in a stoichiometric ratio, purified by washing with water and distillation under reduced pressure, and evaluated by detection using a gas chromatograph-mass spectrometer model 7890A/5975C of agilent usa. The source of the alkyl ester type compound used in the examples of the present invention was purchased from chemical products companies on the market.

Compared with the prior art, the invention has found that a secondary amide/alkyl ester composite solvent composed of the compounds shown in the formula (I) and the formula (II) is used as a new extraction system, so that a new extraction method for separating calcium from calcium-containing brine and extracting lithium and application thereof are obtained, and unexpected effects are achieved. The invention has the following advantages:

1) the secondary amide as the substance A in the extraction system has simple molecular structure, easily obtained source, easy production and extraction effect, is a novel special-effect component for separating calcium from calcium-containing brine and extracting lithium, wherein the secondary amide functional group is a key part for separating and extracting lithium from lithium and calcium, and hydrogen atoms on N-H are arranged before and after extraction¹Shift of H NMR spectrum to low field, for Li⁺Plays a key role in the extraction. The alkyl ester used as B substance in extraction system is easy to be extracted from organic synthesisThe composite solvent is low in price, can effectively improve the physical properties such as viscosity, freezing point and the like of the composite solvent, increases the entropy and entropy of a system, and generates a synergistic effect.

2) In ensuring Li⁺On the premise of single-stage extraction capacity with a certain size, the loaded organic phase is compatible and easy to be directly back-extracted by water, and acid does not need to be used for strengthening Li⁺The back extraction does not need to use alkali to neutralize the acid in the front to restore the extraction capacity of the organic phase and the acid-base property of the aqueous phase, the acid-base consumption is low, the bidirectional balance of the extraction and back extraction processes is realized, and the Li is extracted⁺While also facilitating Li⁺Back extraction of (4). After the calcium-containing brine is subjected to multi-stage countercurrent extraction, the lithium-calcium separation coefficient is large, and the mass ratio of calcium to lithium in the water phase after back extraction is obviously reduced.

3) The whole extraction and separation process is simple, the organic phase is directly recycled, the corrosion degree of equipment is low, and the production process is easy to control. The low density of the organic phase is suitable for the two-phase separation when the loaded organic phase is back-extracted with water. By adjusting the molecular structure and composition of the extraction system, the solubility of the preferred extraction system in water is significantly reduced compared to the solubility of TBP.

Drawings

FIG. 1 is a block diagram of the process flow for the extraction system, extraction method and application of the present invention for separating calcium from calcium-containing brine using a secondary amide/alkyl ester composite solvent to extract lithium.

Table 25 shows the common names, corresponding canonical names and code numbers of the secondary amides of substance A referred to in the examples of the present invention.

Table 26 shows the common names, corresponding specification names and CAS numbers of the alkyl esters of the substances B mentioned in the examples of the present invention.

Detailed Description

The invention is further illustrated by the following examples:

example 1

Certain calcium-containing brine Li⁺And Ca²⁺The content of the calcium is 3.79g/L and 221.99g/L respectively, the mass ratio of the calcium to the lithium is 58.62:1, wherein, Na⁺、 K⁺、Mg²⁺、Cl^-And B₂O₃The contents are respectively 0.83,5.32, 2.03, 424.10 and 2.42g/L, brine density of 1.44g/cm³The pH value of the brine is 5.5, the ion concentration of the brine is prepared according to the composition of the brine of an oil field in south winged mountain of Qinghai diesel wood basin, and the oil field brine is deoiled in advance by an oil-water separator. 6mL of the brine is taken in a 100mL ground conical flask, then 21mL of N-isooctyl isovaleramide extractant and 9mL of ethyl laurate synergistic extractant are added into the flask, the volume of the synergistic extractant occupies 30 percent of the volume of an organic phase, and the volume ratio of the organic phase to the brine is 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 20min at 20 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4000r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:5 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 20 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The extraction rate E, the back-extraction rate S, the partition ratio D, and the lithium-calcium separation coefficient β were calculated from the concentrations, and the results are shown in table 1.

TABLE 1 Complex solvent of N-isooctyl isovaleramide and ethyl laurate for Li in certain calcium-containing brine⁺With Ca²⁺Two-phase separation of^*

^*Wherein the meaning of the symbols is respectively specifiedIs composed of^a: the temperature of the extraction is controlled by the temperature,^b: the volume ratio of the organic phase to the aqueous phase,^c：Li⁺the extraction rate is higher than that of the raw materials,^d：Ca²⁺the extraction rate is higher than that of the raw materials,^e：Li⁺the proportion of the ingredients is distributed according to the formula,^f：Ca²⁺the proportion of the ingredients is distributed according to the formula,^g: the separation coefficient of lithium and calcium is high,^h: the mass ratio of calcium to lithium in the organic phase after extraction,ⁱ: the mass ratio of calcium to lithium in the extracted brine;^j: the back-extraction temperature is higher than the normal temperature,^k: the volume ratio of water to the organic phase,^l：Li⁺the back-extraction rate of the copper is improved,^m：Ca²⁺the back-extraction rate of the copper is improved,ⁿ：Li⁺the distribution ratio of the back extraction is controlled,^o：Ca²⁺the distribution ratio of the back extraction is controlled,^p: the back-extraction separation coefficient of the lithium and the calcium,^q: the mass ratio of calcium to lithium in the organic phase after back extraction,^r: the mass ratio of calcium to lithium in the water phase after back extraction; the same applies to the symbols in tables 2 to 24 below.

As can be seen from Table 1, Li⁺The single-stage extraction rate is 37.66 percent, and the content of Ca is²⁺The single-stage extraction rate is 5.10%, and the lithium-calcium separation coefficient is 11.26. Li⁺The single-stage back extraction rate was 75.68%, Ca²⁺The single-stage back extraction rate is 84.13%, the lithium-calcium separation coefficient after back extraction is 0.58, and the mass ratio of calcium to lithium in the water phase is reduced to 8.83.

Example 2

Certain calcium-containing brine Li⁺And Ca²⁺The content of the calcium is 4.04g/L and 224.03g/L respectively, the mass ratio of calcium to lithium is 55.46:1, wherein Na⁺、 K⁺And Cl^-The contents are respectively 0.88, 5.68 and 423.91g/L, and the brine density is 1.45g/cm³Adjusting the pH value of the brine to 1.9, and removing oil from the oil field brine by using an oil-water separator in advance. 6mL of the brine is taken in a 100mL ground conical flask, then 21mL of N-isooctyl isovaleramide extractant and 9mL of ethyl laurate synergistic extractant are added into the flask, the volume of the synergistic extractant occupies 30 percent of the volume of an organic phase, and the volume ratio of the organic phase to the brine is 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 20min at 20 ℃. The mixed liquid was then transferred to a 100mL plastic test cartridgeCentrifuging for 8min at 4000r/min in an LD5-10 desk centrifuge, separating phases to obtain extracted bittern sample and loaded Li⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:5 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 20 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated and the results are shown in Table 2.

TABLE 2 Complex solvent of N-isooctyl isovaleramide and ethyl laurate for Li in certain calcium-containing brine⁺With Ca²⁺Two-phase separation of

As can be seen from Table 2, Li⁺The single-stage extraction rate is 43.17 percent, and the content of Ca is²⁺The single-stage extraction rate is 5.43%, and the lithium-calcium separation coefficient is 13.21. Li⁺Single stage back extraction of 69.26%, Ca²⁺The single-stage back extraction rate is 80.64%, the lithium-calcium separation coefficient after back extraction is 0.54, and the mass ratio of calcium to lithium in the aqueous phase is reduced to 8.13.

Example 3

Certain calcium-containing brine Li⁺And Ca²⁺The content of the calcium is 3.62g/L and 222.28g/L respectively, the mass ratio of the calcium to the lithium is 61.33:1, wherein, Na⁺、 K⁺And Cl^-The content of the brine is respectively 0.79, 5.09 and 419.79g/L, and the brine density is 1.44g/cm³The pH value of the brine is 1.2, and the oil field brine is deoiled by an oil-water separator in advance. 6mL of this brine was taken in a 100mL ground flask and then 21mL of N-isooctyl iso-acetate was added to the brineThe valeramide extractant and 9mL ethyl myristate synergic extractant occupy 30% of the volume of an organic phase, and the volume ratio of the organic phase to brine is 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting at 10 ℃ for 20 min. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4000r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:5 of the loaded organic phase into the ground conical flask, placing the ground conical flask and the organic phase into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 10 ℃ for 20 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated and the results are shown in Table 3.

TABLE 3 Complex solvent of N-isooctyl isovaleramide and ethyl myristate against Li in certain calcium-containing brine⁺With Ca²⁺Two-phase separation of

As can be seen from Table 3, Li⁺The single-stage extraction rate is 63.40 percent, and the content of Ca is²⁺The single-stage extraction rate is 9.45%, and the lithium-calcium separation coefficient is 16.60. Li⁺Single stage back extraction of 62.39%, Ca²⁺The single-stage back extraction rate is 73.09%, the lithium-calcium separation coefficient after back extraction is 0.61, and the mass ratio of calcium to lithium in the water phase is reduced to 10.71.

Example 4

Extract 24mL of N-pentylisononanamideThe extractant and 6mL ethyl decanoate synergist are put in a 100mL ground conical flask, and the synergist occupies 20% of the volume of the organic phase. Then 6mL of the brine of example 2 was added thereto, the volume ratio of organic phase to brine being 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 20min at 20 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4000r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:5 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 20 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated and the results are shown in Table 4.

TABLE 4N-pentylisononanamide and ethyl decanoate complex solvent vs. Li in certain calcium-containing brine⁺With Ca²⁺Two-phase separation of

As can be seen from Table 4, Li⁺The single-stage extraction rate is 50.68 percent, and the content of Ca is²⁺The single-stage extraction rate is 7.27%, and the lithium-calcium separation coefficient is 13.12. Li⁺The single-stage back extraction rate was 67.88%, Ca²⁺The single-stage back extraction rate is 78.91%, the lithium-calcium separation coefficient after back extraction is 0.57, and the mass ratio of calcium to lithium in the water phase is reduced to 9.27.

Example 5

Certain calcium-containing brine Li⁺And Ca²⁺The content of the calcium is 3.28g/L and 193.13g/L respectively, the mass ratio of calcium to lithium is 58.86:1, wherein Na is⁺、 K⁺And Cl^-The content of the brine is respectively 0.67, 4.29 and 366.88g/L, and the brine density is 1.41g/cm³Adjusting the pH value of the brine to 1.1, and removing oil from the oil field brine by using an oil-water separator in advance. 6mL of this brine was taken in a 100mL ground conical flask, then 22.5 mL of N-pentylisononamide extractant and 7.5mL of hexyl hexanoate synergist were added, the synergist accounted for 25% of the volume of the organic phase, and the volume ratio of the organic phase to the brine was 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting at 10 ℃ for 20 min. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4000r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding water according to the volume ratio of 1:5 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 10 ℃ for 20 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated and the results are shown in Table 5.

TABLE 5N-Pentylisononanamide and hexyl hexanoate complex solvent vs Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation of

As can be seen from table 5, it is,Li⁺the single-stage extraction rate is 34.15 percent, and the content of Ca is²⁺The single-stage extraction rate is 2.46%, and the lithium-calcium separation coefficient is 20.59. Li⁺The single-stage back extraction rate is 83.98 percent, and Ca is²⁺The single-stage back extraction rate is 92.38%, the lithium-calcium separation coefficient after back extraction is 0.43, and the mass ratio of calcium to lithium in the water phase is reduced to 4.66.

Example 6

9mL of N-isobutyl isononanoamide (heated liquid), 12mL of N-isooctyl isovaleramide extractant and 9mL of methyl laurate synergistic extractant were placed in a 100mL ground flask, the volume of the extractant occupied by the extractant was 30%, and then 6mL of the calcium-containing brine of example 2 was added thereto, and the volume ratio of the organic phase to the calcium-containing brine was 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 20min at 20 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4000r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding water according to the volume ratio of 1:5 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 20 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated and the results are shown in Table 6.

TABLE 6 Complex solvent of N-isobutyl isononamide, N-isooctyl isovaleramide and methyl laurate for Li in certain calcium-containing brine⁺With Ca²⁺Two-phase separation of

As can be seen from Table 6, Li⁺The single-stage extraction rate is 44.99 percent, and the content of Ca is²⁺The single-stage extraction rate is 3.66%, and the lithium-calcium separation coefficient is 21.52. Li⁺Single stage stripping yield of 62.46%, Ca²⁺The single-stage back extraction rate is 72.16%, the lithium-calcium separation coefficient after back extraction is 0.64, and the mass ratio of calcium to lithium in the water phase is reduced to 5.21.

Example 7

10.5mL of N-isobutylisononanoamide (liquid after heating), 10.5mL of N-pentylisononanoamide extractant, and 9mL of decyl decanoate synergist were taken in a 100mL ground flask, the synergist occupying 30% of the volume of the organic phase. Then 6mL of the brine of example 2 was added thereto, the volume ratio of organic phase to brine being 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 20min at 20 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4000r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:5 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 20 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated and the results are shown in Table 7.

TABLE 7 composite solvent of N-isobutyl isononanamide, N-pentyl isononanamide and decyl caprate on Li in certain calcium-containing brine⁺With Ca²⁺Two-phase separation of

As can be seen from Table 7, Li⁺The single-stage extraction rate is 48.78 percent, and the content of Ca is²⁺The single-stage extraction rate is 8.18%, and the lithium-calcium separation coefficient is 10.68. Li⁺Single stage back extraction of 63.68%, Ca²⁺The single-stage back extraction rate is 77.47%, the lithium-calcium separation coefficient after back extraction is 0.51, and the mass ratio of calcium to lithium in the water phase is reduced to 11.31.

Example 8

6mL of the calcium-containing brine of example 3 was taken in a 100mL ground conical flask, 0.85g of ferric chloride hexahydrate of 99% purity was added to dissolve the calcium-containing brine, and then 10.5mL of N-isobutylisononanoamide (heated liquid), 10.5mL of N-isooctyl isovaleramide extractant and 9mL of methyl laurate were added, the extractant occupied 30% of the volume of the organic phase, and the volume ratio of the organic phase to the brine was 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 20min at 20 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4000r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:5 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 20 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated and the results are shown in Table 8.

TABLE 8 Complex solvent of N-isobutylisononanamide, N-isooctyl isovaleramide and methyl laurate for certain Fe-containing compounds³⁺Li in brine⁺With Ca²⁺Two-phase separation of

As can be seen from Table 8, Li⁺The single-stage extraction rate is 54.02 percent, and the content of Ca is²⁺The single-stage extraction rate is 8.17%, and the lithium-calcium separation coefficient is 13.20. Li⁺The single-stage back extraction rate was 77.62%, Ca²⁺The single-stage back extraction rate is 74.49%, the lithium-calcium separation coefficient after back extraction is 1.19, and the mass ratio of calcium to lithium in the water phase is reduced to 8.90.

Example 9

2mL of N-ethyl lauramide (liquid after heating), 8mL of N-amyl isononamide extractant and 10mL of ethyl myristate synergist were taken in a 100mL ground conical flask, and the synergist accounted for 50% of the volume of the organic phase. Then 2mL of calcium-containing brine is added into the mixture, and the volume ratio of the organic phase to the brine is 10: 1. Li in the calcium-containing brine⁺、Ca²⁺And Cl^-The contents of the components are respectively 0.28, 210.92 and 374.58g/L, the mass ratio of calcium to lithium is equal to 746.37:1, and the density of brine is 1.41g/cm³The pH value of the brine is 6.0. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 30min at 0 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4200r/min, obtaining a brine sample after extraction and a Li load after phase separation, wherein the interface of two phases is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:20 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 0 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic test cartridge in a model LD5-10 bench top centrifugeCentrifuging at 4200r/min for 8min to obtain organic phase and water phase after back extraction.

Respectively adopting a Japanese Shimadzu AA-7000 type atomic absorption spectrophotometer standard addition method and an EDTA volumetric titration method to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated and the results are shown in Table 9.

TABLE 9 composite solvent of N-Ethyl lauramide, N-pentylisononanamide and Ethyl myristate with respect to Li in certain calcium-containing brine⁺With Ca²⁺Two-phase separation of

As can be seen from Table 9, Li⁺The single-stage extraction rate is 40.64 percent, and the content of Ca is²⁺The single-stage extraction rate is 10.61%, and the lithium-calcium separation coefficient is 5.77. Li⁺Single stage back extraction rate of 40.74%, Ca²⁺The single-stage back extraction rate is 39.31%, the lithium-calcium separation coefficient after back extraction is 1.06, and the mass ratio of calcium to lithium in the water phase is reduced to 187.96.

Example 10

19mL of N-amyl isononanamide, 1mL of N-isooctyl-1-cyclopropyl formamide, 1mL of N-hexyl-3-cyclopentyl propionamide as an extractant and 9mL of ethyl myristate as a synergist were put into a 100mL ground conical flask, the synergist occupied 30% of the volume of the organic phase, and then 6mL of the calcium-containing brine obtained in example 9 was added thereto, and the volume ratio of the organic phase to the calcium-containing brine was 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 30min at 20 ℃. Then transferring the mixed liquid into a 100mL plastic test tube, centrifuging for 8min in a desk type centrifuge of LD5-10 model at the rotating speed of 4200r/min, and separating the phases to obtain the final productExtracted brine sample and loaded Li⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:5 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4200r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a Japanese Shimadzu AA-7000 type atomic absorption spectrophotometer standard addition method and an EDTA volumetric titration method to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 10.

TABLE 10 Complex solvent of N-pentylisononanamide, N-isooctyl-1-cyclopropylcarboxamide, N-hexyl-3-cyclopentylpropionamide and ethyl myristate against Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation of

As can be seen from Table 10, Li⁺The single-stage extraction rate is 49.90 percent, and the content of Ca is²⁺The single-stage extraction rate is 5.53%, and the lithium-calcium separation coefficient is 17.01. Li⁺The single-stage back extraction rate was 81.58%, Ca²⁺The single-stage back extraction rate is 92.97%, the lithium-calcium separation coefficient after back extraction is 0.33, and the mass ratio of calcium to lithium in the water phase is reduced to 94.26.

Example 11

9.8mL of N-pentylisononanamide, 0.1mL of N-ethyllauramide (liquid after heating), 0.1mL of N-cyclopropyldecanoamide (liquid after heating), 9.9mL of ethyl myristate synergist and 0.1mL of No. 260 mineral oil (supplied by Wenyang speciality oil Co., Ltd., the same applies hereinafter) diluent were placed in a 100mL ground conical flask, wherein the synergist and diluent accounted for 49.5% and 0.5% of the volume of the organic phase, respectively. Then 2mL of calcium-containing brine is added, and the volume ratio of the organic phase to the brine isIs 10: 1. Li in the calcium-containing brine⁺、 Ca²⁺And Cl^-The contents of the brine are respectively 4.15, 253.03 and 472.38g/L, the mass ratio of calcium to lithium is equal to 60.91:1, and the density of the brine is 1.52g/cm³The pH value of the brine is 1.0. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting at 50 ℃ for 30 min. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4200r/min, obtaining a brine sample after extraction and a Li load after phase separation, wherein the interface of two phases is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:10 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 50 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4200r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a Japanese Shimadzu AA-7000 type atomic absorption spectrophotometer standard addition method and an EDTA volumetric titration method to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 11.

TABLE 11 Complex System of N-pentylisononamide, N-ethyllauramide, N-cyclopropyldecanoamide, ethyl myristate and No. 260 mineral oil against Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation of

As can be seen from Table 11, Li⁺The single-stage extraction rate is 37.42 percent, and the content of Ca is²⁺The single-stage extraction rate is 0.59%, and the lithium-calcium separation coefficient is 100.75. Li⁺The single-stage back extraction rate is 50.17 percent, and Ca is added²⁺The single-stage back extraction rate is 55.96%, the lithium-calcium separation coefficient after back extraction is 0.79,the mass ratio of calcium to lithium in the water phase is reduced to 1.06.

Example 12

9.8mL of N-pentylisononanamide, 0.2mL of N-isooctylneodecanoamide extractant, 0.1mL of dodecyl isobutyrate synergist and 9.9mL of No. 260 solvent oil diluent were placed in a 100mL ground conical flask, where the synergist and diluent accounted for 0.5% and 49.5% of the volume of the organic phase, respectively. Then 2mL of the calcium containing brine of example 9 was added thereto, the volume ratio of the organic phase to the calcium containing brine being 10: 1. Inserting a polytetrafluoroethylene stirring rod into the conical flask, mixing and stirring at 50 deg.C with a DW-1-60 type DC constant speed stirrer, and extracting for 30 min. Then naturally clarifying and settling the mixed liquid for 60min, and separating two phases to obtain an extracted brine sample and a loaded Li⁺、Ca²⁺The organic phase of (a). The loaded organic phase was transferred to another 100mL ground flask, deionized water was added at a volume ratio of 1:10 to the organic phase, a Teflon stir bar was inserted, back extraction was performed at 50 ℃ with a DW-1-60 model constant-current stirrer, and the two phases were mixed for 30 min. And naturally clarifying and settling the mixed liquid for 60min, and separating two phases to obtain an organic phase and a water phase after back extraction.

Respectively adopting a Japanese Shimadzu AA-7000 type atomic absorption spectrophotometer standard addition method and an EDTA volumetric titration method to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 12.

TABLE 12 Complex System of N-pentylisononanamide, N-isooctylneodecanoamide, dodecyl isobutyrate, and No. 260 mineral spirit for Li in certain calcium-containing brine⁺With Ca²⁺Two-phase separation of

As can be seen from Table 12, Li⁺The single-stage extraction rate is 43.73 percent, and the content of Ca is²⁺The single-stage extraction rate is 0.38%, and the lithium-calcium separation coefficient is 203.74. Li⁺Single-stage back extraction rate of 48.00% and Ca²⁺The single-stage back-extraction rate is 44.42%,the lithium-calcium separation coefficient after back extraction is 1.16, and the mass ratio of calcium to lithium in the water phase is reduced to 6.00.

Example 13

15.8mL of N-amyl isononanoamide, 0.2mL of N-cyclododecyl acetamide (heated liquid) extractant and 4mL of methyl laurate synergistic extractant are put into a 100mL ground conical flask, the synergistic extractant occupies 20% of the volume of an organic phase, then 2mL of calcium-containing brine is added, and the volume ratio of the organic phase to the calcium-containing brine is 10: 1. Li in the calcium-containing brine⁺、Ca²⁺And Cl^-The contents of the brine are respectively 23.87, 179.61 and 439.65g/L, the mass ratio of calcium to lithium is equal to 7.52:1, and the density of the brine is 1.40g/cm³The pH value of the brine is 6.5. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 30min at 30 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4200r/min, obtaining a brine sample after extraction and a Li load after phase separation, wherein the interface of two phases is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:10 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 30 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4200r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a Japanese Shimadzu AA-7000 type atomic absorption spectrophotometer standard addition method and an EDTA volumetric titration method to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 13.

TABLE 13 Complex solvent of N-pentylisononanamide, N-cyclododecylacetamide and methyl laurate for Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation of

As can be seen from Table 13, Li⁺The single-stage extraction rate is 33.05 percent, and the content of Ca is²⁺The single-stage extraction rate is 2.24%, and the lithium-calcium separation coefficient is 21.32. Li⁺The single-stage back extraction rate was 87.61%, Ca²⁺The single-stage back extraction rate is 89.19%, the lithium-calcium separation coefficient after back extraction is 0.94, and the mass ratio of calcium to lithium in the aqueous phase is reduced to 0.52.

Example 14

19.3mL of N-pentylisononanamide, 0.5mL of N-isooctylbutanamide extractant, 0.1mL of hexyl acetate synergist, and 0.1mL of 300# mineral oil diluent were placed in a 100mL ground conical flask, where the extractant accounted for 99% of the volume of the organic phase, the synergist, and the diluent accounted for 0.5% and 0.5% of the volume of the organic phase, respectively. Then 2mL of calcium-containing brine is added into the mixture, and the volume ratio of the organic phase to the brine is 10: 1. Li in the calcium-containing brine⁺、Ca²⁺And Cl^-The contents of the brine are respectively 2.51, 147.61 and 273.95g/L, the mass ratio of calcium to lithium is equal to 58.80:1, and the density of the brine is 1.30g/cm³The pH value of the brine is 5.3. Putting a magneton into a ground conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing, putting the conical flask into a DF-101S heat collection type constant temperature heating magnetic stirrer, mixing and stirring at 20 ℃, and extracting for 30 min. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4300r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:10 of the loaded organic phase, placing the mixture into a DF-101S heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4300r/min for 8min in a model LD5-10 bench top centrifuge to yield the back-extracted organic and aqueous phases.

Respectively adopting a Japanese Shimadzu AA-7000 type atomic absorption spectrophotometer standard addition method and an EDTA volumetric titration method to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes and preparing the mixtureAnalysis of the solution, sampling for Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 14.

TABLE 14 Complex System of N-Pentylisononanamide, N-isooctylbutanamide, hexyl acetate and No. 300 mineral spirits for Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation of

As can be seen from Table 14, Li⁺The single-stage extraction rate is 36.75 percent, and the content of Ca is²⁺The single-stage extraction rate is 1.56%, and the lithium-calcium separation coefficient is 36.66. Li⁺Single stage back extraction of 88.69%, Ca²⁺The single-stage back extraction rate is 84.71 percent, the lithium-calcium separation coefficient after back extraction is 1.42, and the mass ratio of calcium to lithium in the water phase is reduced to 2.37.

Example 15

17.82mL of N-amyl isononanoamide extractant, 0.1mL of dodecyl isobutyrate and 0.08mL of isopropyl palmitate co-extractant are put in a 100mL ground conical flask, wherein the extractant and the co-extractant respectively account for 99 percent and 1 percent of the volume of the organic phase. Then 9mL of the calcium containing brine of example 9 was added thereto, the volume ratio of the organic phase to the calcium containing brine being 2: 1. Putting a magneton into a ground conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing, putting the conical flask into a DF-101S heat collection type constant temperature heating magnetic stirrer, mixing and stirring at 30 ℃, and extracting for 30 min. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4300r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:2 of the loaded organic phase to the organic phase, placing the mixture into a DF-101S heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 30 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4300r/min for 8min in a model LD5-10 bench top centrifuge to yield the back-extracted organic and aqueous phases.

Respectively adopting a Japanese Shimadzu AA-7000 type atomic absorption spectrophotometer standard addition method and an EDTA volumetric titration method to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 15.

TABLE 15N-pentylisononanamide, lauryl isobutyrate, and isopropyl palmitate complex solvent vs. Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation of

As can be seen from Table 15, Li⁺The single-stage extraction rate is 45.86 percent, and the content of Ca is²⁺The single-stage extraction rate is 1.78%, and the lithium-calcium separation coefficient is 46.74. Li⁺The single-stage back extraction rate was 42.63%, Ca²⁺The single-stage back extraction rate is 77.93%, the lithium-calcium separation coefficient after back extraction is 0.21, and the mass ratio of calcium to lithium in the water phase is reduced to 52.96.

Example 16

8.75mL of N-pentylisononanamide, 0.25mL of N-ethyl-1- (4-pentylcyclohexyl) carboxamide extractant, 0.09mL of ethyl myristate synergist, and 8.91mL of No. 260 mineral oil diluent were placed in a 100mL ground flask, where the extractant accounted for 50% of the volume of the organic phase, the synergist, and the diluent accounted for 0.5% and 49.5% of the volume of the organic phase, respectively. Then 1.8mL of calcium-containing brine was added thereto, the volume ratio of the organic phase to the brine was 10: 1. Li in the calcium-containing brine⁺、Ca²⁺And Cl^-The contents of the components are respectively 0.41, 212.60 and 378.21 g/L, the mass ratio of calcium to lithium is equal to 515.53:1, and the density of brine is 1.41g/cm³The pH value of the brine is 6.1. Putting a magneton into a ground conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing, putting the conical flask into a DF-101S heat collection type constant temperature heating magnetic stirrer, mixing and stirring at 0 ℃ and extracting for 30 min. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4300r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、 Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:10 of the loaded organic phase, placing the mixture into a DF-101S heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 0 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4300r/min for 8min in a model LD5-10 bench top centrifuge to yield the back-extracted organic and aqueous phases.

Respectively adopting a Japanese Shimadzu AA-7000 type atomic absorption spectrophotometer standard addition method and an EDTA volumetric titration method to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 16.

TABLE 16 Complex System of N-pentylisononanamide, N-ethyl-1- (4-pentylcyclohexyl) carboxamide, Ethyl myristate and No. 260 mineral oil against Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation of

As can be seen from Table 16, Li⁺The single-stage extraction rate is 34.66 percent, and the content of Ca is²⁺The single-stage extraction rate is 1.08%, and the lithium-calcium separation coefficient is 48.59. Li⁺The single-stage back extraction rate is 95.55 percent, and Ca is added²⁺The single-stage back extraction rate is 93.76%, the lithium-calcium separation coefficient after back extraction is 1.43, and the mass ratio of calcium to lithium in the water phase is reduced to 15.76.

Example 17

19.6mL of N-pentylisononanamide, 0.2mL of N- (4-tert-butylcyclohexyl) octanoylamide extractant, and 0.2mL of ethyl myristate synergist were taken in a 100mL ground flask, where the extractants and synergist accounted for 99% and 1% of the organic phase volume, respectively. Then 10mL of calcium-containing brine is added into the mixture, and the volume ratio of the organic phase to the brine is 2: 1. Li in the calcium-containing brine⁺、Ca²⁺And Cl^-The contents of the components are respectively 0.21, 211.56 and 375.33g/L, the mass ratio of calcium to lithium is equal to 1007.43:1, and the density of brine is 1.41g/cm³The pH value of the brine is 6.5. Putting a magneton into a ground conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing, putting the conical flask into a DF-101S heat collection type constant temperature heating magnetic stirrer, mixing and stirring at 20 ℃, and extracting for 30 min. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4300r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:2 of the loaded organic phase, placing the mixture into a DF-101S heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4300r/min for 8min in a model LD5-10 bench top centrifuge to yield the back-extracted organic and aqueous phases.

Respectively adopting a Japanese Shimadzu AA-7000 type atomic absorption spectrophotometer standard addition method and an EDTA volumetric titration method to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated and the results are shown in Table 17.

TABLE 17 combination of N-pentylisononanamide, N- (4-tert-butylcyclohexyl) octanamide, and ethyl myristate solvent vs. Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation of

As can be seen from Table 17, Li⁺The single-stage extraction rate is 33.21 percent, and the content of Ca is²⁺The single-stage extraction rate is 8.86%, and the lithium-calcium separation coefficient is 5.11. Li⁺The single-stage back extraction rate is 65.00 percent, and Ca is²⁺The single-stage back extraction rate is 87.62%, the lithium-calcium separation coefficient after back extraction is 0.26, and the mass ratio of calcium to lithium in the aqueous phase is reduced to 362.30.

Example 18

15mL of N-amyl isononanoamide extractant, 7.5mL of ethyl decanoate and 7.5mL of methyl myristate are taken as synergistic extractantsIn a 100mL ground flask, the synergist contained 50% of the volume of the organic phase. Then 3mL of calcium-containing brine is added, and the volume ratio of the organic phase to the brine is 10: 1. Li in the calcium-containing brine⁺、Ca²⁺And Cl^-The contents of the calcium and the lithium are respectively 3.99, 274.10 and 508.82g/L, the mass ratio of calcium to lithium is equal to 68.65:1, and the density of brine is 1.54g/cm³The pH value of the brine is 1.0. Putting a magneton into a ground conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing, putting the conical flask into a DF-101S heat collection type constant temperature heating magnetic stirrer, mixing and stirring at 20 ℃, and extracting for 30 min. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4300r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:10 of the loaded organic phase, placing the mixture into a DF-101S heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4300r/min for 8min in a model LD5-10 bench top centrifuge to yield the back-extracted organic and aqueous phases.

Respectively adopting a Japanese Shimadzu AA-7000 type atomic absorption spectrophotometer standard addition method and an EDTA volumetric titration method to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 18.

TABLE 18 Complex solvent of N-pentylisononanamide, ethyl decanoate and methyl myristate vs. Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation of

As can be seen from Table 18, Li⁺The single-stage extraction rate is 39.75 percent, and the content of Ca is²⁺The single-stage extraction rate is 3.57%, and the lithium-calcium separation coefficient is 17.81. Li⁺Single stage back extraction of 72.79%, Ca²⁺The single-stage back extraction rate is 64.24%, the lithium-calcium separation coefficient after back extraction is 1.49, and the mass ratio of calcium to lithium in the water phase is reduced to 5.45.

Example 19

19mL of N-pentylisononanamide, 1.4mL of N-dodecylacetamide as extractant and 3.6mL of methyl myristate as co-extractant were taken in a 100mL ground flask, the co-extractant occupying 15% of the volume of the organic phase. Then 4mL of calcium-containing brine is added, and the volume ratio of the organic phase to the brine is 6: 1. Li in the calcium-containing brine⁺、Ca²⁺And Cl^-The contents of the components are respectively 0.094 g/L, 178.60 g/L and 316.43g/L, the mass ratio of calcium to lithium is equal to 1900.00:1, and the density of brine is 1.36g/cm³The pH value of the brine is 7.0. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 30min at 20 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4200r/min, obtaining a brine sample after extraction and a Li load after phase separation, wherein the interface of two phases is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:6 of the loaded organic phase to the organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4200r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 19.

TABLE 19 combination of N-pentylisononanamide, N-dodecylacetamide, and methyl myristate solvent vs. Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation of

As can be seen from Table 19, Li⁺The single-stage extraction rate is 34.75 percent, and the content of Ca is²⁺The single-stage extraction rate is 5.36%, and the lithium-calcium separation coefficient is 9.41. Li⁺The single-stage back extraction rate was 66.11%, Ca²⁺The single-stage back extraction rate is 64.91%, the lithium-calcium separation coefficient after back extraction is 1.05, and the mass ratio of calcium to lithium in the water phase is reduced to 287.75.

Example 20

13.5mL of N-pentylisononanamide as an extractant and 1.5mL of ethyl myristate as a synergist were taken in a 100mL ground flask, the synergist occupying 10% of the volume of the organic phase, and then 15mL of the calcium-containing brine of example 9 was added thereto, the volume ratio of the organic phase to the calcium-containing brine being 1: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 30min at 20 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4200r/min, obtaining a brine sample after extraction and a Li load after phase separation, wherein the interface of two phases is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:1 of the loaded organic phase to the organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4200r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 20.

TABLE 20 combination of N-pentylisononanamide and ethyl myristate solvent vs. Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation ofSituation(s)

As can be seen from Table 20, Li⁺The single-stage extraction rate is 30.12 percent, and the content of Ca is²⁺The single-stage extraction rate is 1.90%, and the lithium-calcium separation coefficient is 47.53. Li⁺Single stage back extraction of 68.62%, Ca²⁺The single-stage back extraction rate is 69.29 percent, the lithium-calcium separation coefficient after back extraction is 0.97, and the mass ratio of calcium to lithium in the water phase is reduced to 47.54.

Example 21

10.5mL of N-isooctyl isovaleramide, 10.5mL of N-amyl isononamide extractant and 9mL of methyl myristate synergist were taken in a 100mL ground conical flask, and the synergist accounted for 30% of the volume of the organic phase. Then 6mL of the calcium containing brine of example 3 was added thereto, the volume ratio of the organic phase to the calcium containing brine being 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 20min at 20 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4000r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). And then, carrying out three-stage countercurrent extraction according to the extraction cascade cross operation steps to obtain a loaded organic phase and a residual brine phase after the three-stage countercurrent extraction.

Transferring the loaded organic phase after the three-stage countercurrent extraction to another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:5 of the loaded organic phase to the organic phase, placing the mixture in a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing for 20min at the temperature of 20 ℃. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 21.

TABLE 21 Complex solvent of N-isooctyl isovaleramide, N-amyl isononanamide and methyl myristate against Li in certain calcium-containing brine⁺With Ca²⁺Three stage counter current extraction and single stage back extraction conditions of

As can be seen from Table 21, Li was obtained after three-stage countercurrent extraction of brine⁺The extraction rate was 62.07%, Ca²⁺The extraction rate was 4.83%, and the lithium-calcium separation coefficient was 32.31. Li⁺Single stage back extraction of 76.57%, Ca²⁺The single-stage back extraction rate is 86.09 percent, the lithium-calcium separation coefficient after back extraction is 0.53, the mass ratio of calcium to lithium in the water phase is reduced to 5.37, and Li in brine⁺With Ca²⁺Effective separation is achieved. The more the multistage countercurrent extraction stages are, the more Li in brine⁺The higher the extraction rate and the higher the lithium-calcium separation coefficient are, the more the multistage countercurrent back-extraction stages are under the condition of reducing the water phase consumption, the more the Li in the water phase after back-extraction is favored⁺The concentration is increased. Further improves the stage number of countercurrent extraction and countercurrent back extraction, and Li⁺The extraction rate and the back-extraction rate of (2) are further improved, while Ca²⁺The extraction rate of (a) is basically unchanged.

And returning the back-extracted organic phase to be mixed with the brine phase before extraction again, thereby realizing the recycling of the extractant.

Then the aqueous phase solution obtained after back extraction is deoiled and concentrated to Li through double-effect evaporation⁺After the concentration is 30g/L, sodium sulfate and sodium carbonate solution are respectively added to completely precipitate and remove Ca in the solution²⁺Respectively adding barium chloride and sodium hydroxide solution to completely precipitate and remove sulfate radical and Mg²⁺Then, thenAnd evaporating and concentrating, cooling and crystallizing, filtering and drying the residual solution to obtain the anhydrous lithium chloride product.

And (3) placing the lithium chloride concentrated solution obtained after impurity removal and refining in an ion membrane electrolytic cell for electrolysis to obtain a lithium hydroxide solution with the mass concentration of 12% at the cathode, concentrating and crystallizing to obtain lithium hydroxide monohydrate, and washing and drying to obtain the anhydrous lithium hydroxide product. Meanwhile, hydrogen and chlorine are produced as by-products, and the hydrogen and the chlorine are further reacted to prepare hydrochloric acid.

Example 22

10.5mL of N-isooctyl isovaleramide, 10.5mL of N-amyl isononamide extractant and 9mL of hexyl hexanoate synergist were placed in a 100mL ground conical flask, the synergist accounted for 30% of the volume of the organic phase, and then 6mL of the calcium-containing brine of example 5 was added thereto, and the volume ratio of the organic phase to the calcium-containing brine was 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting at 10 ℃ for 30 min. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4000r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). And then, carrying out three-stage countercurrent extraction according to the extraction cascade cross operation steps to obtain a loaded organic phase and a residual brine phase after the three-stage countercurrent extraction.

Transferring the loaded organic phase after the three-stage countercurrent extraction to another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:5 of the loaded organic phase to the organic phase, placing the mixture in a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 10 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase. And then carrying out secondary countercurrent back extraction according to a cascade cross operation step to obtain an organic phase and a water phase after the secondary countercurrent back extraction.

Respectively adopting a Nippon Shimadzu AA-7000 type atomic absorption spectrophotometer standard addition method and EDTA titrationThe method comprises the steps of carrying out constant volume on a brine phase and a water phase in the extraction and back extraction processes, preparing an analysis solution, sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 22.

TABLE 22 Complex solvent of N-isooctyl isovaleramide, N-amyl isononanamide and hexyl hexanoate for Li in certain calcium-containing brine⁺With Ca²⁺In the case of three-stage countercurrent extraction and two-stage countercurrent back-extraction

As can be seen from Table 22, Li was obtained after three-stage countercurrent extraction of brine⁺The extraction rate was 51.83%, Ca²⁺The extraction rate is 2.34%, and the lithium-calcium separation coefficient is 45.05. Li after the loaded organic phase is subjected to secondary counter-current back extraction⁺The back extraction was 84.34%, Ca²⁺The back extraction rate is 92.83 percent, the lithium-calcium separation coefficient after back extraction is 0.42, the mass ratio of calcium to lithium in the water phase is reduced to 2.92, and Li in the brine⁺With Ca²⁺Effective separation is achieved. Further improves the stage number of countercurrent extraction and countercurrent back extraction, and Li⁺And B₂O₃The extraction rate and the back-extraction rate of (2) are further improved, while Ca²⁺The extraction rate of (a) is kept substantially constant.

Then the aqueous phase solution obtained after back extraction is deoiled and concentrated to Li through double-effect evaporation⁺After the concentration is 20g/L, sodium sulfate and sodium carbonate solution are respectively added to completely precipitate and remove Ca in the solution²⁺Respectively adding barium chloride and sodium hydroxide solution to completely precipitate and remove sulfate radical and Mg²⁺To obtain a lithium chloride refined solution. Then adding sodium carbonate solution with the concentration of 250 g/L into the lithium carbonate solution according to 1.1 times of the theoretical dosage of the lithium carbonate solution to generate lithium carbonate precipitate, and filtering and drying the lithium carbonate precipitate to obtain a lithium carbonate product.

Adding calcium hydroxide emulsion into the obtained lithium carbonate, heating and strongly stirring to carry out solid-liquid reaction to generate lithium hydroxide solution and calcium carbonate precipitate, separating two phases to obtain lithium hydroxide solution, carrying out reduced pressure concentration, crystallization and drying at 130-140 ℃ to obtain lithium hydroxide monohydrate, and then carrying out reduced pressure heating at 150-180 ℃ to obtain the anhydrous lithium hydroxide product.

Comparative example 1

40mL of amyl valerate were taken as the extractant in a 100mL ground Erlenmeyer flask, to which was then added 8mL of the calcium containing brine of example 5, the volume ratio of extractant to calcium containing brine being 5: 1. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 30min at 20 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4000r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:5 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 23.

TABLE 23 pentanoic acid amyl ester solvent vs. Li in certain calcium-containing brine⁺With Ca²⁺Two-phase separation of

As can be seen from Table 23, Li at this time⁺The single-stage extraction yield was only 2.87% very small, indicating that the alkyl ester solvent is responsible for Li in the brine⁺The extraction capacity is not large, and the composite solvent mixed with secondary amide and alkyl ester has the effect of separating lithium and calcium in the brineIn significant contrast. This comparative example serves as a counter example to the previous example and further illustrates the role of secondary amides in extraction.

Comparative example 2

40mL of ethyl nonanoate as extractant were placed in a 100mL ground flask and then 8mL of the calcium-containing brine from example 5 was added thereto at a 5:1 ratio by volume of extractant to calcium-containing brine. Putting a magneton into a conical flask, inserting a matched air condenser pipe into the mouth of the conical flask to prevent liquid from splashing out, placing the conical flask into a DF-101S type heat collection type constant temperature heating magnetic stirrer, and mixing, stirring and extracting for 30min at 20 ℃. Then transferring the mixed liquid into a 100mL plastic test cylinder, centrifuging for 8min in an LD5-10 desktop centrifuge at the rotating speed of 4000r/min, obtaining an extracted brine sample and a loaded Li after phase separation, wherein the two-phase interface is clear⁺、Ca²⁺The organic phase of (a). Transferring the loaded organic phase into another 100mL ground conical flask, adding deionized water according to the volume ratio of 1:5 of the loaded organic phase, placing the mixture into a DF-101S type heat collection type constant-temperature heating magnetic stirrer, and carrying out back extraction and two-phase mixing at 20 ℃ for 30 min. The combined liquid was then transferred to a 100mL plastic cartridge and centrifuged at 4000r/min for 8min in a model LD5-10 bench top centrifuge to yield a back-extracted organic and aqueous phase.

Respectively adopting a standard addition method of an AA-7000 type atomic absorption spectrophotometer and an EDTA titration method in the Shimadzu corporation to perform constant volume on the brine phase and the water phase in the extraction and back extraction processes, preparing an analysis solution, and sampling and analyzing Li⁺And Ca²⁺The concentrations were calculated, and the results are shown in Table 24.

TABLE 24 Ethyl nonanoate solvent vs Li in certain calcium-containing brines⁺With Ca²⁺Two-phase separation of

From table 24 can seeOut when Li is present⁺The single-stage extraction rate is only 1.47% very small, indicating that the alkyl ester solvent is opposite to Li in the brine⁺The extraction capacity is not large, and the lithium-calcium separation effect of the composite solvent mixed with the secondary amide and the alkyl ester in the brine is remarkably compared. This comparative example serves as a counter example to the previous example and further illustrates the role of secondary amides in extraction.

The above embodiments are only some examples provided for the selection of the present invention, and the embodiments of the present invention are not limited by the above embodiments. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, combination, and improvement made within the spirit and principle of the present invention and various changes in form and details thereof are within the protection scope of the present invention.

Table 25 common names, corresponding canonical names and designations for the secondary amides of substance A referred to in the examples

Serial number	Secondary amides of part A substances common names	Part A substance secondary amides correspond to the canonical names	(Code)
				1	N-isooctylbutanamide	N- (2-ethylhexyl) butanamide	Z842
2	N-isobutyl radicalIsononanoamides	N- (2-methylpropyl) -3,5, 5-trimethylhexanamide	Z494
				3	N-isooctyl isovaleramide	N- (2-ethylhexyl) -3-methylbutanamide	Z854
4	N-Ethyl lauramide	N-Ethyl N-dodecanoic acid amide	Z2121
				5	N-pentylisononanamides	N-N-pentyl-3, 5, 5-trimethylhexanamide	Z593
6	N-dodecyl acetamide	N-N-dodecyl acetamide	Z1221
				7	N-isooctyl neodecanoamide	N- (2-ethylhexyl) -7, 7-dimethyloctanamide	Z8104
8	N-isooctyl-1-cyclopropylcarboxamide	N- (2-ethylhexyl) -1-cyclopropylcarboxamide	Z84h2
				9	N-Cyclopropyldecanoamide	N-cyclopropyl-N-decanamide	Z3h101
10	N-ethyl-1- (4-pentylcyclohexyl) carboxamide	N-ethyl-1- (4-N-pentylcyclohexyl) carboxamide	Z212h1
				11	N-cyclododecyl acetamide	N-cyclododecyl acetamide	Z12h21
12	N-hexyl-3-cyclopentylpropionamides	N-N-hexyl-3-cyclopentyl propionamide	Z68h1
				13	N- (4-tert-butylcyclohexyl) octanoyl amide	N- (4-tert-butylcyclohexyl) N-octanoylamide	Z10h82

Common names, corresponding specification names and CAS numbers for the alkyl esters of substance B referred to in the examples of Table 26^*

^*CAS number is american chemical abstracts registry number.

Claims

1. An extraction system for separating calcium from calcium-containing brine by using a secondary amide/alkyl ester composite solvent to extract lithium, which is characterized in that the extraction system contains A and B substances; wherein the A-type substance is a secondary amide and consists of a single compound or a mixture of more than two compounds; wherein the single compound has a structure as shown in formula (I):

(I)；

wherein R is₁Selected from C2-C12 alkyl or C3-C12 cycloalkyl containing single ring structure, R₂Selected from C1-C11 alkyl or C3-C11 cycloalkyl containing single ring structure, and R₁And R₂The sum of the numbers of carbon atoms contained in the two groups is 11 to 17, wherein the alkyl or cycloalkyl group includes various isomers; when R is₁、R₂When uniquely identified, class A is a single compound, and mixtures thereof refer to compounds that follow R₁、R₂A mixture of two or more compounds produced by the change of (1);

(Ⅱ)；

wherein R is₃Selected from C1-C12 alkyl, R₄Selected from C1-C15And R is alkyl of₃And R₄The sum of the number of carbon atoms contained in the two alkyl groups is 7-19, wherein the alkyl groups contain various straight-chain or branched isomers; when R is₃、R₄When uniquely identified, class B is a single compound, and mixtures thereof refer to compounds that follow R₃、R₄A mixture of two or more compounds produced by the change of (1);

the freezing point of the extraction system containing the substances A and B is less than 0 ℃.

2. The extraction system for separating calcium from calcium-containing brine and extracting lithium by using a secondary amide/alkyl ester composite solvent according to claim 1, wherein the extraction effect of the A-type substance accounts for 50-100% of the whole organic phase by volume, and the A-type substance does not account for 100% of the whole organic phase by volume; the B-type substance has a synergistic effect, and accounts for 0-50% of the whole organic phase by volume, excluding 0% of the end point.

3. An extraction system for separating calcium from calcium-containing brine and extracting lithium by using secondary amide/alkyl ester composite solvent as claimed in claim 1, wherein said extraction system comprising substances A and B further comprises diluent 260# solvent oil, 300# solvent oil or sulfonated kerosene for dilution.

4. An extraction process for separating calcium from a calcium-containing brine using a secondary amide/alkyl ester composite solvent to extract lithium, comprising the steps of:

s2, using the secondary amide/alkyl ester composite solvent as described in any claim 1 to 3 as organic phase before extraction;

5. The extraction method for separating calcium from calcium-containing brine and extracting lithium using a secondary amide/alkyl ester composite solvent according to claim 4, wherein the calcium-containing brine further contains one or more of sodium ion, potassium ion, magnesium ion, iron ion, ferrous ion, boric acid, and borate ion.

6. The extraction process of claim 4, wherein the calcium-containing brine comprises a lithium-containing oil field brine or a lithium-containing underground brine.

7. The extraction method for separating calcium from calcium-containing brine and extracting lithium by using a secondary amide/alkyl ester composite solvent as claimed in claim 4, wherein in the step S3, the extraction temperature is 0-50 ℃; the mixing of the two phases is carried out by stirring, and the separation of the two phases after extraction is carried out by a centrifugal separation mode or a clarification and sedimentation mode.

8. The extraction process for separating calcium from calcium-containing brine to extract lithium using secondary amide/alkyl ester composite solvent as claimed in claim 4, further comprising the step of, after said step S3:

9. The extraction method for separating calcium from calcium-containing brine and extracting lithium by using a secondary amide/alkyl ester composite solvent as claimed in claim 8, wherein in the step S4, the back extraction temperature is 0-50 ℃; the two-phase mixing is carried out by a stirring mode, and the two-phase separation after back extraction is carried out by a centrifugal separation mode or a clarification and sedimentation mode.

10. Use of the extraction method of claim 8 or 9 for separating calcium from calcium-containing brine using secondary amide/alkyl ester composite solvent to extract lithium for obtaining lithium chloride product, wherein after step S4, the method further comprises the steps of:

11. Use of the extraction process for separating calcium from calcium-containing brine using secondary amide/alkyl ester composite solvent as claimed in claim 8 or 9 for extracting lithium to obtain lithium carbonate as lithium product, characterized by further comprising, after said step S4, the steps of:

12. Use of the extraction process for separating calcium from calcium-containing brine using secondary amide/alkyl ester composite solvent as claimed in claim 8 or 9 for extracting lithium to obtain lithium hydroxide product, wherein after said step S4, further comprising the steps of:

or after the step S6, the method further includes the steps of: